The preparation of homopolymers and copolymers of polymerizable unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and the like, optionally with other vinylidene monomers and small amounts of cross-linking agents, to form water sensitive polymers is well known. These materials are usually prepared by polymerization of the monomers in the presence of free radical forming catalysts in an organic medium that is a solvent for the monomers, but a nonsolvent for the resulting polymers, in a closed stirred vessel. During the course of the polymerization process, beginning shortly after initiation of polymerization, polymer begins to precipitate from the solution as it is formed. This precipitate often begins to flocculate and form aggregates, causing the reaction mixture to thicken and become difficult to handle and stir. This results in many processing problems, including poor heat transfer, overheating in unstirred areas, localization of unreacted monomer, fouling of reactor surfaces, and irreproducible polymers.